Zest the lemon. Put the zest in your food processor bowl. Return the lemon, wrapped, to the fridge for another use.
Zest the orange; add to food processor bowl. Juice the orange; add to food processor bowl as well.
Now add all remaining ingredients to food processor bowl and whiz until well blended.
Transfer batter to cake pan, place in oven, and bake for 45 to 55 minutes or until a toothpick or skewer come out clean and top is golden. Let cool in the pan.
Notes
Use a round cake pan that is 9 x 2 inch (23 x 5 cm) or that will hold 8 cups (2 L).